System and method for determining the rotational alignment of drillstring elements

Abstract

A rotational alignment system determines the angular relationship between two or more elements of a drill string using one or more sensors that detect one or more reference objects positioned on the drill string. A control unit determines the rotational or angular offset between two or more elements on the drill string using measurements made by the sensor(s). In one application, rotational offset values are used by a surface logging computer to correlate sensor data provided by a logging tool.

1. An apparatus for determining a relative rotational position of two or more wellbore tool elements having a fixed angular relationship, comprising:
 at least one sensor sensing a section of the wellbore tool having the two or more elements and generating a responsive signal; and 
 a processor configured to receive the responsive signal from the at least one sensor and determine the relative rotational position of the two or more elements using the responsive signal. 
 
     
     
       2. The apparatus of  claim 1  wherein the at least one sensor is one of: (i) an optical sensor, (ii) an infrared sensor and (iii) a magnetic field sensor. 
     
     
       3. The apparatus of  claim 1  wherein the at least one sensor is positioned at a surface location the processor is a general purpose computer. 
     
     
       4. The apparatus of  claim 1  wherein the responsive signal includes an image of at least the section of the wellbore tool. 
     
     
       5. The apparatus of  claim 1  further comprising a surface logging computer configured to receive the determined relative rotational position from the processor. 
     
     
       6. The apparatus of  claim 1  further comprising a transmitter transmitting the responsive signal from the at least one sensor to the processor using one of (i) a wire, and (ii) a wireless transmission device. 
     
     
       7. The apparatus of  claim 1  further comprising at least one reference object positioned on the well bore tool. 
     
     
       8. The apparatus of  claim 7  wherein the at least one reference object is a discontinuity on a surface of the wellbore tool. 
     
     
       9. The apparatus of  claim 8  wherein the discontinuity is one of: (i) a depression, (ii) a raised portion, and (iii) a magnetic signal. 
     
     
       10. A method for determining a relative rotational position of two or more wellbore tool elements having a fixed angular relationship, comprising:
 sensing a section of the wellbore tool having the two or more elements with at least one sensor; 
 generating a signal in response to the sensed section of the wellbore tool; and 
 determining the relative rotational position of the two or more elements using the responsive signal using a processor. 
 
     
     
       11. The method of  claim 10  wherein the at least one sensor is one of: (i) optical sensor, (ii) an infrared sensor and (iii) a magnetic field sensor. 
     
     
       12. The method of  claim 10  wherein the sensing is done at the surface and the processor is a general purpose computer. 
     
     
       13. The method of  claim 10  wherein generating the signal includes imaging at least the section of the wellbore tool. 
     
     
       14. The method of  claim 10  further comprising transmitting the determined relative rotational position from the processor to a surface logging computer. 
     
     
       15. The method of  claim 14  further comprising:
 measuring a parameter of interest in the wellbore; 
 determining a wellbore highside in the wellbore; and 
 correlating the measured parameter of interest with wellbore highside using the surface logging computer. 
 
     
     
       16. The method of  claim 10  further comprising positioning at least one reference object on the well bore tool. 
     
     
       17. The method of  claim 16  further comprising detecting the at least one reference object using the at least one sensor. 
     
     
       18. A system for determining a relative rotational position of two or more wellbore tool elements having a fixed angular relationship of a wellbore tool, comprising:
 a rig at a surface location configured to convey the wellbore tool into a wellbore; 
 at least one sensor positioned on the rig, the at least one sensor configured to sense a section of the wellbore tool having the two or more elements and generate a responsive signal; and 
 a processor configured to receive the responsive signal from the at least one sensor and determine the relative rotational position of the two or more elements using the responsive signal. 
 
     
     
       19. The system of  claim 18  further comprising a surface logging computer configured to receive the determined relative rotational position from the processor. 
     
     
       20. The system of  claim 19  further comprising:
 at least one logging tool in the wellbore tool, the at least one logging tool being configured to measure at least one parameter of interest; and 
 an orientation measurement sensor in the wellbore tool, the orientation measurement sensor being configured to determine a wellbore highside; 
 wherein the surface logging computer is further configured to correlate the measured parameter of interest with wellbore highside.